How to securely splice a wire

Simple steps to get your ride back in the action

A fix that anyone can do!

I was recently helping a fellow RCer with an issue he was having with the radio glitching on his nitro monster truck. Upon inspection, I discovered that one of the wire leads going to the receiver was badly damaged. The insulation was worn through thus exposing the wire strands underneath. The radio glitching was caused by the wire strands coming into contact with the metal chassis. I spliced the wires for him and the glitching was eliminated.

I have found that many people get a bit intimidated when it comes to performing repairs to the electronics on their vehicles. Something like a damaged wire is actually quite easy and quick to repair and it will save you the money it cost to have the hobby shop do it or for the replacement of the damaged component. In this article I will show you how you can repair a damaged wire on your radio system along with a trick for making the new connection extra secure.

STEP 1: Remove component from vehicle

Once you have located the damaged wire, remove that component from the chassis so that you donít risk damaging anything else on the vehicle during the repair. Like from the intense heat created by the soldering iron.

STEP 3: Strip the ends of the wire

Strip off about one quarter inch of insulation off either end of the wire to be spliced back together. This step can be carefully done using a hobby knife or a wire stripping tool. Be careful not to cut too deeply and into the wire strands just under the surface of the insulation.

STEP 4: Install heat shrink tubing

Before you join the ends of the wires together, slide a piece of heat shrink tubing onto one of the wires. Make sure that it is not only long enough to cover the exposed wire strands, but to also overlap on either side. This piece of heat shrink will then be slid into place after the wire has been soldered back together.

STEP 5: Twist the wire ends together

Line up each piece of wire so that they are parallel to each other. In other words, the exposed wire is next to each other and the insulated portions are next to each other. Now twist the wire together several times.

This differs from the method where you splice wire by butting it up against each other and then twisting the wire. I find that when working with small gauge wire, like what is used on servos and receiver battery packs, it is more effective to twist the wire leads together when they are side by side. When the wires are butt up against one another, it is not easy to get them securely wound around each other.

STEP 6: Apply flux to wires

I see people skipping this step, but I always apply flux to the wires being soldered together as it helps facilitate a good solder joint. Flux acts as a cleaning agent and helps to make the solder flow.

STEP 7: Solder wires together

Once the soldering iron is up to temperature, clean the tip of the iron and then place it on the wires. You will see the flux Ďmeltí away almost immediately and that is a good cue to introduce the solder to the wires. Make sure you keep the wires still until the solder starts to cool. You will know that you achieved a good solder joint if it is shiny and not dull.

STEP 8: Cover joint with heat shrink tubing

Once the wire has completely cooled, bend the soldered section onto the wire and then slide the heat shrink tubing from ďSTEP 4Ē over the newly spliced wire. Make sure it is positioned so that it completely covers the joint and overlaps on each side. Use a lighter or heat gun to shrink the tubing onto the wire and now it is insulated again. Now all that is left is to reinstall the newly repaired component back into the vehicle.

Good tutorial. I do wonder if the final step of bending one piece of wire over, to make the shrink tube fit better, won't induce a new weak point though. Some wires don't hold up well when bent over that way.

Good tutorial. I do wonder if the final step of bending one piece of wire over, to make the shrink tube fit better, won't induce a new weak point though. Some wires don't hold up well when bent over that way.

To eliminate that worry, you can just overlap the stripped ends and solder.

Good tutorial. I do wonder if the final step of bending one piece of wire over, to make the shrink tube fit better, won't induce a new weak point though. Some wires don't hold up well when bent over that way.

It is possible that some wires might not be to 'happy' with the bend, but in my experience with servo and receiver wire leads, they can handle the bend. I always like to have the wiring nice and tidy in my cars so when there is excess wiring, I bundle it together and use zip-ties to hold it together. Like the image shown here. This way it helps eliminate the chance of the excess wiring getting caught up in the drivetrain or other moving parts.

Another way to do this that provides a good mechanical joint is to form a hook at the end of each stripped wire, then hook them together and solder. You won't have to bend anything after the solder cools down, and you'll be left with a nice strong joint that will be able to sustain tension. You can even wrap each hook end around the opposite wire before soldering. Don't go crazy with twisting the wires. Just 1 or 2 turns is enough.

Another way to do this that provides a good mechanical joint is to form a hook at the end of each stripped wire, then hook them together and solder. You won't have to bend anything after the solder cools down, and you'll be left with a nice strong joint that will be able to sustain tension. You can even wrap each hook end around the opposite wire before soldering. Don't go crazy with twisting the wires. Just 1 or 2 turns is enough.

It is possible that some wires might not be to 'happy' with the bend, but in my experience with servo and receiver wire leads, they can handle the bend. I always like to have the wiring nice and tidy in my cars so when there is excess wiring, I bundle it together and use zip-ties to hold it together. Like the image shown here. This way it helps eliminate the chance of the excess wiring getting caught up in the drivetrain or other moving parts.

There is a difference in bending a contiguous (no splices or discontinuities) stranded wire vs bending the solder spliced wire that you showed.

The issue is soldering wicking into the wire, essentially turning it into a solid wire combined with a sharp bend right at the transition from solid to stranded.
This can lead to a condition called "birdsnesting".

It is preferable to not place bends at such transitions, rather, as mentioned by other poster, just overlap the ends, solder the wires, apply heatshrink well past the joint and then, if necessary, make your bend past the heatshrink.
This keeps the bend on stranded wire only, eliminating any issues with birdnesting.

Images

In the case of the servo pictured above it is very easy to simply open back plate of servo and unsolder the wire, cut to proper length and re solder.

I've done servos all they way down to HS55 with a full size iron. Yes a pencil is easier though.

Depending on the application a butt joint will be either simply lapped or twisted. The most important thing I think is proper wire retention though. Any solder joint will fail if the wires are flopping all over the place.

Soldering is far smaller than crimping but most of our cars and trucks we drive everyday are crimped.